The present invention pertains, in general, to the identification and use of Telomerase Reverse Transcriptase (TERT) genes and the proteins encoded by such genes. In particular, the present invention pertains to the identification and use of TERT genes and TERT proteins from several genetically diverse and economically important organisms, including two human pathogens and an agronomic crop species.
All publications and patent applications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
TERT genes have been identified in mammals (mouse and human), yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe) and ciliated protozoans (Tetrahymena thermophila, Oxytricha trifallax and Euplotes aediculatus) (Ligner, J. et al., 1997; Bryan, T. M. et al., 1998; Nakamura, T. M. at al., 1997; Greenberg, R. A. et al., 1999). Telomerase RNA has been cloned from bovine testis (Tsao et al., 1998) and from approximately twenty other organisms.
The protein encoded by the TERT gene, together with an RNA subunit, comprise telomerase, an enzyme required for the maintenance of telomeres. Telomeres, which are long stretches of short DNA sequence repeats located on the ends of linear chromosomes, are an essential component of the eukaryotic genome. They serve as xe2x80x9ccapsxe2x80x9d on chromosomal termini, preventing loss of terminal sequence information and degradation of chromosomal DNA, as well as regulating expression of nearby genes. Telomerase has been shown to be responsible for maintenance of telomere length, as cells lacking this enzyme experience a shortening and eventual loss of telomeric sequence. For a recent review, see Bryan and Cech, 1999.
Telomere length and telomerase activity have been implicated in studies of both aging and cancer. Telomeres are believed to function as a molecular clock, gradually shortening as a cell ages and signaling cell death when the telomeres decay down to a critical length. It has been observed that in many immortal cells, telomerase appears to be overactive, resulting in telomeres that are maintained indefinitely. These observations have led to great interest in research programs attempting to develop pharmaceuticals that either ameliorate or activate telomerase activity, as well as diagnostic tools to detect telomerase activity. For reviews, see Raymond, 1996 and Holt and Shay, 1999.
We have identified TERT genes from three economically important and genetically diverse organisms: Plasmodium falciparum, Candida albicans and Oryza sativa. P. falciparum and C. albicans are the causative agents of serious medical conditions of humans while O. sativa is food staple of people throughout the world, especially those of third world countries. The discovery of these genes will have a profound effect on our ability to genetically manipulate and control the growth of these important organisms.
This invention comprises compositions and methods for the identification and use of novel TERT genes. In particular, this invention provides comprises compositions and methods for the identification and use of TERT genes of Plasmodium falciparum, Candida albicans and Oryza sativa. 
The present invention provides isolated nucleic acid molecules coding for TERT genes and TERT gene fragments wherein the isolated nucleic acid molecules include: (a) isolated nucleic acid molecules that encode the amino acid sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10; (b) isolated nucleic acid molecules that encode a fragment of at least 6 amino acids of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10; (c) isolated nucleic acid molecules which hybridize to the complement of a nucleic acid molecule comprising SEQ ID NO.1, SEQ ID NO.3, SEQ ID NO.5, SEQ ID NO.7 or SEQ ID NO.9 under conditions of sufficient stringency to produce a clear signal; and (d) isolated nucleic acid molecules which hybridize to a nucleic acid molecule that encodes the amino acid sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10 under conditions of sufficient stringency to produce a clear signal. In particular, this invention provides nucleic acid molecules with the nucleic acid sequences of SEQ ID NO.1, SEQ ID NO.3, SEQ ID NO.5, SEQ ID NO.7 and SEQ ID NO.9.
This invention also provides such isolated nucleic acid molecules coding for TERT genes or gene fragments operably linked to one or more expression control elements.
This invention also provides vectors comprising such isolated nucleic acid molecules coding for TERT genes and TERT gene fragments.
This invention also provides host cells, tissues, organs and organisms transformed to contain such nucleic acid molecules coding for TERT genes and TERT gene fragments. This invention further provides host cells, tissues, organs and organisms comprising vectors comprising such isolated nucleic acid molecules coding for TERT genes and TERT gene fragments.
This invention also provides methods for producing a polypeptide comprising the step of culturing a host cell transformed with such nucleic acid molecules coding for TERT genes and gene fragments under conditions in which the protein encoded by these nucleic acid molecules are expressed. This invention further provides isolated polypeptides produced by such methods.
This invention also provides isolated TERT polypeptides and TERT polypeptide fragments wherein the polypeptides include: (a) those coded by the amino acid sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10; (b) those comprising a fragment of at least 6 amino acids of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10; (c) conservative amino acid substitutions of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10; and (d) naturally occurring amino acid sequence variants of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
The invention also provides isolated antibodies that bind to such TERT polypeptides and TERT polypeptide fragments. The invention further provides such antibodies wherein the antibodies are monoclonal or polyclonal antibodies.
The invention also provides methods of identifying an agents which modulate the expression of a nucleic acid encoding the protein having the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10 comprising the steps of:
exposing cells which express the nucleic acid to the agent; and
determining whether the agent modulates expression of said nucleic acid, thereby identifying an agent which modulates the expression of a nucleic acid encoding the protein having the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
The invention also provides methods of identifying agents which modulate at least one activity of a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10 comprising the steps of:
exposing cells which express the protein to the agent;
determining whether the agent modulates at least one activity of said protein, thereby identifying an agent which modulates at least one activity of a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
The invention also provides methods of identifying binding partners for a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10, comprising the steps of:
exposing said protein to a potential binding partner; and
determining if the potential binding partner binds to said protein, thereby identifying binding partners for a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
The invention also provides methods of modulating the expression of a nucleic acid encoding the protein having the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10 comprising the step of:
administering an effective amount of an agent which modulates the expression of a nucleic acid encoding the protein having the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
This invention also provides methods of modulating at least one activity of a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10 comprising the step of:
administering an effective amount of an agent which modulates at least one activity of a protein comprising the sequence of SEQ ID NO.2, SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 or SEQ ID NO.10.
This invention also provides methods for diagnosing Plasmodium falciparum infection in a patient comprising the steps of:
obtaining a cell sample from the patient;
determining whether the nucleic acid of SEQ ID NO.5 or SEQ ID NO.7 or the protein of SEQ ID NO.6 or SEQ ID NO.8 is present within the cell sample; and
correlating the presence of the nucleic acid of SEQ ID NO.5 or SEQ ID NO.7 or the protein of SEQ ID NO.6 or SEQ ID NO.8 with the presence of Plasmodium falciparum. 
This invention also provides methods for diagnosing Candida albicans infection in a patient comprising the steps of:
obtaining a cell sample from the patient;
determining whether the nucleic acid of SEQ ID NO.1 or SEQ ID NO.3 or the protein of SEQ ID NO.2 or SEQ ID NO.4 is present within the cell sample; and
correlating the presence of the nucleic acid of SEQ ID NO.1 or SEQ ID NO.3 or the protein of SEQ ID NO.2 or SEQ ID NO.4 with the presence of Candida albicans. 
One skilled in the art can easily make any necessary adjustments in accordance with the necessities of the particular situation.
Further objects and advantages of the present invention will be clear from the description that follows.